Conventionally, wire harnesses that are to be arranged in, for example, vehicles and the like are assembled on an assembly drawing plate on which instructions regarding the lengths of electric wires and connectors for connecting the wires, and instructions regarding mounting of exterior components such as corrugated tubes and protectors, and the like are indicated (see Patent Document 1 below, JP 2012-104258A). Based on an assembly drawing on the assembly drawing plate, an assembly operator lays out electric wires, bands the laid out electric wires together into a bundle, connects electric components such as connectors to the electric wires, and performs other operations to assemble a wire harness. The assembly drawing plate is provided with a plurality of supports for supporting the electric wires and the connectors, and the wire harness is supported by the plurality of supports, and is held at predetermined positions on the assembly drawing plate.